Rotatably mounted muffler assembly



June 30, 1953 P. E. SCHMID 2,643,731

ROTATABLY MOUNTED MUFFLER ASSEMBLY Filed 001;. 50, 1948 2 Sheets-Sheet 1 June 30, 1953 P. E. 5cm"; 2,643,731

ROTATABLY MOUNTED MUFFLER ASSEMBLY Filed Oct. 30, 1948 2 Sheets-Sheet 2 A T TORNEY \III Patented June 30, 1953 ROTATABLY MOUNTED MUFFLER ASSEMBLY Paul E. Schmid, Houston, Tex., assignor to Reed Roller Bit Company, Houston,

tion of Texas Tex., a corpora- Application October 30, 1948, Serial No. 57,570 3 Claims. (Cl. 181-55) This invention pertains broadly to compressed air actuated tools, but more particularly to an exhaust muliler therefor constructed to reduce the noise of the exhaust air and mounted on the tool in a manner enabling the exhaust jet to be directed away from the operator.

In compressed air actuated tools or motors, either of the percussive or rotary type, the compressed air after having down through the tool and acted upon parts to impart motion thereto, is suddenly released to the outside of the tool. This sudden exhaust and consequential expansion of the compressed air creates a considerable amount of noise which is annoying and detrimental to the operator and persons in his vicinity. In an effort to reduce such noise, several attempts have been made to equip such tools with exhaust mufi'lers, but their size, weight or complicated construction have rendered them impractical.

It is therefore one object of this invention to produce an exhaust muiiier for fluid or compressed air actuated tools, which is of simple construction, small size and weight, and effective in reducing the exhaust noise.

Another object of this invention is to produce such a mufiler which comprises only three inexpensive parts assembled together to form a single unit.

Another object of this invention is to provide a compressed. air actuated tool with an exhaust muiiler fitted on the tool in a manner enabling the direction of the exhaust jet to be changed at will.

Other objects and advantages more or less ancillary to the foregoing and the manner in which all the various objects are attained will appear the following description, which considered in connection with the accompanying drawings, sets forth the preferred embodiment of the invention.

In the drawings:

Figure l is a longitudinal View, partly in section, of a compressed air actuated tool embodying the invention.

Figure 2 is a cross-sectional View taken through line 2-2 in Figure 1.

Figure 3 is a longitudinal sectional view of the muffler assembly as shown in Figure 1.

Figure 4 is a cross sectional View taken through line d& in Figure 3.

Figure 5 is a longitudinal view of the mufiler assembly shown in the same position as shown in Figures 1 and 4.

Referring to the drawings in which like symbols designate corresponding parts throughout the several views, I0 represents the rear housing of a compressed air actuated rotary tool, which tool is of the usual type and includes a compressed air inlet connection I I secured within the housing I I]. Admission of the motive fluid to the tool is controllable by a throttle valve I2, adequately mounted within the housin It] and operable by a throttle valve handle or lever I3, which has one end pivotally connected to the housing I!) by a cross pin I4.

Interiorly, the housing It is machined to accommodate two longitudinally spaced bearing plates I5 and I6 mounted coaxially and having a cylinder or stator I'I extending between them and held stationary relative to the housing ill by a dowel I8 which extends through the bearing plate, I 5. The stator I I is provided with a cylindrical rotor chamber I9 extending therethrough and closed at both ends by the bearing plates I5 and I6. This chamber is located with its center axis parallel to that of the bearing plates but in offset relation therewith.

Rotatably mounted within the rotor chamber I9, there is the main cylindrical portion of a rotor 20 which extends from one bearing plate to the other and has reduced end portions 2| and 22 extending into the bearing plates I5 and I6 respectively where they are adequately supported in bearings 23. The rotor end 22 extends into a front housing 24 where it is drivingly connected to the spindle of a work performing tool, not shown, for imparting rotation thereto.

As is customary in a rotary tool of this type, the main body portion of the rotor 26 is provided with four, equally spaced, radially extending slots 25, each having slidable therein a blade or vane 26 engageable with the inner wall of the rotor chamber I9. As clearly shown in Figure 2, the rotor '20 is disposed eccentrically within the chamber I 9 to such an extent as to provide a line contact 21 with the inner wall thereof.

The exterior of the stator machined to form, after it is assembled into the rear housing If), two chambers 28 and 29 located adjacent to and one on each side of the line contact 27. The chamber 28 is in constant communication with the rotor chamber I9 through a plurality of ports 30, while the chamber 28 similarly in communication with the rotor cham ber I9 through a plurality of ports 3I.

Diametrically opposed to the line contact 27, there is provided, between the stator 51 and rear cylinder I 0, an exhaust chamber 32 of substantially crescent shape cross section and extending longitudinally between the bearing plates I5 and IE but falling short of the ends of the stator as I! is appropriately 3 clearly shown in Figure 1. This chamber is in communication with the rotor chamber l9 through a plurality of aligned exhaust ports 33.

Since the construction above described is equivalent to that of the usual compressed air actuated rotary tool, no further description is thought necessary, other than pointing out that in tools of this type the exhaust ports, such as 33, generally lead from the equivalent of the exhaust chamber 32 to the atmosphere without any provision being made to muffle or reduce the noise thus caused by the exhausting fluid.

The above detailed description of the tool has been given in order to more clearly set forth the invention about to be described. To that end, it might also be well to briefly explain the opera tion of the tool, which operation is also common to all tools of this type, and is as follows:

Compressed, air is admitted from a source of supply such as a compressor, into the rear housing I through the inlet connection. H. With the throttle valve it open, the-compressed air is admitted. through passageways, not shown, into one or the other of the chambers 28 and 25. Since the tool, shown and described of the reversible type, compressed air may be admitted. into the chamber 28 for effecting rotation of the rotor 2d in a clockwise direction as seen in Figure 2, or in chamber 29 for effecting its counterclockwise rotation. admitted into the chamber 28, it will flow there" from through the ports 35 into the rotor chamber 19 and exert pressure successively on the blades 26 for imparting rotation to the rotor fifl. As each blade uncovers the exhaust ports 33, the compressed fluid. will escape or exhaust from the rotor chamber 19 through the exhaust ports, which ports or their equivalent, as previously mentioned, generally open directly to the atmosphere. In practice, the one of the two chambers 28 and 719, not used as an inlet chamber is generally transformed by means of a suitable valve, not shown, as an exhaust chamber through which, in this instance, compressed fluid still trapped. in the rotor chamber I!) after it has flown over the exhaust ports 33, is free to exhaust through the ports 3 I.

Referring now more particularly to the invention, the external wall portion of the housing Iii which surrounds the exhaust chamber 32, is ac curately machined to form two longitudinally spaced cylindrical bearings 34 and. 35 of equal diameters having between them a cylindrical por-- tion 36 of reduced diameter. The bearing 34 is ended by an annular shoulder 31 while the bear ing 35 is ended by a similar shoulder which constitutes the end wall of the front housing 2%. This housing is preferably screwed on an extension 39 of the housing i0, with the result that the shoulder 38 can be moved toward or away from the shoulder 31.

Closely fitted on the bearings 34 and 35 but rotatable relative thereto, there is a muiller assembly which includes a cylindrical inner sleeve 48 and an annular ring ii of substantially U shape cross section having its ends fitting closely on the inner sleeve 40 where they are preferably secured thereto by any suitable means such as a pressed fit or a spot weld. Between the inner sleeve 4.0 and the outer ring 4i, there is provided an annular chamber 42 filled with porous ma terial having sound absorbing qualities such as a strip of soft felt or the like.

When the muiiler assembly is inserted over the bearings 34 and 35, the diametrically reduced Assuming that the compressed air is v portion 35 located between the bearings, forms with the inner wall of the muffler inner sleeve an annular auxiliary exhaust chamber 5-3 which has a volumetric capacity materially greater than that of the chamber 32. This last chamber is in communication with the exhaust chamber 32 through a plurality of ports 44 extending through the walls of the housing H] which separates the chamber 32 from the chamber 43.

The auxiliary exhaust chamber it is in communication with the muffler chamber 42 through a plurality of holes or exhaust ports iii provided through the wall of the inner sleeve 49. These ports, the number of which may vary, preferably include four groups, each having ports longitudinally aligned within the boundary of the auxiliary exhaust groove 43, with the groups equally spaced from each other.

Extending from the mufiler chamber at to the exterior of the muilier, there is a plurality of ports at provided through the wall of the outer ring ii. These last ports have a combined area substantially equal .to the combined area of the but are concentrated within a small. of the outer ring 41 in order to limit the from which flows the exhaust jet.

In the operation of the device, the exhausting iiuid from the exhaust chamber 552 will now into the auxiliary exhaust chamber it through the ports N. Since the volumetric capaci.+ Y of the auxiliary exhaust chamber 6.3 is materially greater than that of the exhaust chamber the exhausting fluid will immediately expand in the auxiliary chamber 43, thereby reducing its pressure as well as its velocity from the chamber 43 to the exterior of the muiiler. As the exhausting fluid. enters the auxiliary chamber as through the ports 44, it will flow therein in all. directions but generally oircumferentially relative to the bottom of the chamber 43 in opposite directions, thereby enabling an unrestricted flow of the hausting fluid into the chamber 43.

From the chamber 43, the exhaustin i'luid under reduced pressure will enter the mu" chamber 42 through the ports 45. The chamber 42. which is filled with porous material such soft felt, has a volumetric capacity much than that of the auxiliary chamber thereby effecting a further expansion of the exhausting fluid in the muffler chamber as well reducing its pressure and velocity. in this chamber, the exhausting fluid will flow through the porous material such as soft felt which a medium for further retarding the flow of the exhaus" fluid from the ports $5 to the ports '23 where it 3 finally free to reach the exterior of the muiiler. The soft felt contained in the chamber in addition to retarding the flow of the fluid has also noise absorbing qualities which are effective in greatly reducing the noise which would otherwise be occasioned by the new of the exhausting fiuid from the ports it to the exterior of the muffler through the chamber Q2 and ports 46.

Since the muffler assembly is rotatably mounted on the bearings 34 and 35, it may be tiuied at will to change the exhausting jet in any direction suitable to the operation. Normally the front housing 24 is screwed on the projection. of the rear housing it to aiford. frictional resistance between the ends of the muiller and the shoulders 31 and 38 which will enable the operator to turn the muffler in the desired position and will pre-- vent its accidental rotation. If desired, the muffler, after adjustment to its desired position, can

5 be made immovable by clamping it between the shoulders 37 and 38 through the screw thread connection between the two housings Ill and 24.

Although the description of this device is necessarily of a detailed character, in order to completely set forth the invention, it is to be understood that the specific terminology employed is not intended to be restrictive or confining. It is also to be understood that various rearrangements of parts and modifications of structural detail may be resorted to without departing from the scope and spirit of the invention.

I claim:

1. In a fluid actuating tool embodying a housing having two longitudinally spaced cylindrical bearings and an exhaust chamber into which flows exhaust fluid, the combination of an exhaust mufller comprising a sleeve, rotatably mounted on said bearings in concentric relation with said exhaust chamber to define between said bearings an intermediate chamber, said housing having ports therein providing communication between said exhaust chamber and said intermediate chamber, a ring secured to said sleeve in concentric relation therewith and defining a muffler chamber, porous material disposed in said mumer chamber, said sleeve having ports therein providing communication between said intermediate chamber and said mufller chamber, said ring having ports therein communicating with said mufiier chamber, said intermediate chamber having a volumetric capacity greater than that of the exhaust chamber and said muffler chamber having a volumetric capacity greater than that of said intermediate chamber for discharging the exhausting fluid through the ports of said ring at a reduced pressure.

2. In a fluid actuating tool embodying a housing having two longitudinally spaced cylindrical bearings and an apertured exhaust chamber into which flows exhaust fluid, the combination of an exhaust muffler comprising a sleeve rotatably mounted on said bearings in concentric relation with said exhaust chamber to define between said bearings an intermediate chamber, a ring secured to said sleeve in concentric relation therewith and defining a mufller chamber, porous material disposed in said mufiler chamber, said sleeve formed with a plurality of substantially equally spaced groups of ports providing communication between said intermediate chamber and said mufiler chamber, said ring formed with a plurality of ports concentrated within a relatively small area and laterally spaced from the ports in said sleeve.

3. In a fluid actuating tool embodying a housing having two longitudinally spaced cylindrical bearings and a cylindrical portion of reduced diameter therebetween forming the outer wall of an exhaust chamber into which flows exhaust fluid, the combination of an exhaust muffier comprising a sleeve rotatably mounted on said bearings in concentric relation with said exhaust chamber to define with said portion of reduced diameter an intermediate chamber, a ring secured to said sleeve in concentric relation therewith to define a muflier chamber, porous material disposed in said muiiier chamber, said housing having a plurality of aligned ports therein providing communication between said exhaust chamber and said intermediate chamber, said sleeve formed with a plurality of substantially spaced groups of aligned ports arranged circumferentially of the sleeve with respect to the exhaust chamber ports, said sleeve ports providing communication between said intermediate chamber and said muffler chamber, said ring formed with a plurality of ports concentrated within a relatively small area and laterally spaced from the ports in said sleeve.

PAUL E. SCHMID.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 291,762 Nason Jan. 8, 1884 681,522 Very Aug. 27, 1901 713,536 Tobias Nov. 11, 1902 723,111 Winton Mar. 17, 1903 806,714 Porter Dec. 5, 1905 1,115,704 Manes Nov. 3, 1914 1,613,322 Goetz Jan. 4, 1927 2,128,742 Fuehrer Aug. 3, 1938 FOREIGN PATENTS Number Country Date 341,083 Italy June 9, 1936 

